Fuel supply for internal combustion engine



. June 19, 1962 E. A. JOHNSON 3,039,748

FUEL SUPPLY FOR INTERNAL COMBUSTION ENGINE Filed Afi 25, 1958 5SheetsSheet 1 INVENTOR. EL DON A. JOHNSON ATTORNEY June 19, 1962 E, A.JOHNSON 3,039,748

FUEL SUPPLY FOR INTERNAL COMBUSTION ENGINE Filed Aug. 25, 1958 3Sheets-Sheet 2 INVENTOR. ELDON A. JOHNSON ATTORNEY June 19, 1962 E. A.JOHNSON 3,039,748

FUEL SUPPLY FOR INTERNAL COMBUSTION ENGINE Filed Aug. 25, 1958 5Sheets-Sheet 3 ELDON A. JOHNSON ATTORNEY United States Patent J ice3,039,748 Patented June 19, 1962 New Jersey Filed Aug. 25, 1958, Ser.No. 756,953 4 Claims. (Cl. 261-36) This invention relates to fuel supplysystems for internal combustion engines and consists particularly innovel means for preventing excessive pressure build up in the fuel pumpand supply lines, while providing for adequate fuel delivery andefficiency of the pump, improved metering characteristics of thecarburetor, and a considerably simplified and therefore less expensivecarburetor construction.

In my co-pending application, Serial No. 739,267 filed June 2, 1958, nowPatent No. 3,003,753 dated October 10, 1961, and Serial No. 739,268filed June 2, 1958, there are illustrated and claimed various fuelsupply systems for internal combustion engines utilizing carburetorswith constant level chambers of the overflow type and fuel pumpsincorporating scavenger pumps for evacuating the overflow chambers.Thus, even during engine idling, a constant supply of liquid fuel iscirculated from the pump through the carburetor bowl, thence back to thescavenger pump. The scavenger pump is operated by a liquid link from themain pump and during periods of low fuel consumption, the main pumpdiaphragm stroke is only sufficient to deliver fuel in quantifiesslightly in excess of that being consumed by the engine and to producethe recirculating action of the scavenger pump. In those devices, meansare provided for applying back pressure upon the purnp chamber inaccordance with the delivery pressure of the scavenger pump so as tolimit the pump delivery in accordance with fuel demands of the engine.

It is the main object of the present invention to provide arecirculating fuel system incorporating other, somewhat simplified meansfor adjusting the pump delivery in accordance with the engine fuelsupply demands, while insuring a continuous, minimum supply of liquidfuel through the system, even at periods of idling and low loadoperation of the engine.

Another object is to provide means for restricting the fuel deliveryfrom the pump to the carburetor substantially in proportion with engineload and, therefore, fuel demands.

Another object is to provide means for restricting the fuel connectionbetween the pump and carburetor substantially in accordance with enginefuel demand as sensed by the position of the throttle, so that the fuelline and throttle will be in restricting positions and vice versa atsubstantially the same times.

Still another object is to provide means for restricting the fuelconnection between the pump and carburetor under conditions of low loadoperation of the engine, as sensed by a device which responds tomanifold suction.

These objects are accomplished in the present invention which embodies amore or less conventional main fuel pump of the engine-charged,spring-discharged type and also including a scavenger pump which ishydraulically operated from the main pump. The carburetor has a constantlevel fuel bowl of the overflow type having an inlet which is connectedto the outlet of the main fuel pump, the overflow portion of the bowlbeing connected by a duct to the inlet of the scavenger pump. A tubeconnected to the scavenger pump outlet returns the recirculated fuel tothe fuel tank. A restricting valve is provided in the bowl inlet capableof limiting, but not completely cutting off, the fuel supply connectionto the bowl.

The valve may be operated by any device which senses engine load andfuel requirements, in the present instance, either in accordance withthrottle position, or with manifold suction conditions.

In the accompanying drawings Which illustrate the invention,

FIG. 1 is a schematic side view of an automotive chassis and engineillustrating the components of my novel fuel supply system.

FIG. 2 is a top view of the carburetor of FIG. 3 with the bowl coverremoved.

FIG. 3 is a somewhat schematic vertical sectional representation of thefuel pump device and carburetor.

FIG. 4 is a detail section taken on line 44 of FIG. 3.

FIG. 5 is a side view of a pump and carburetor assembly illustrating amodification, portions of the carburetor being broken away andsectioned.

In FIG. 1, there is illustrated a chassis 10 having any suitableinternal combustion engine 11 mounted on the forward portion thereof anda fuel supply tank 12 mounted at the rear. The tank is connected bydelivery and return tubes 13 and 14 to a mechanical fuel pump 15 mountedat the side of crankcase 11a of the engine and operated from the enginecamshaft (not shown) as by a push rod 16 and pivoted lever 17 (FIG. 5).The pump is connected by supply tubing 18 to the carburetor 19 mountedon the engine intake manifold 20 in the customary manner. An engineexhaust manifold is shown at 21. The carburetor bowl 22 (FIGS. 1, 2 and3) is connected to the intake manifold by a tube 23, to be furtherdescribed hereafter.

The carburetor, which is the same in both forms, except for the fuelinlet portion, and is most completely shown in FIGS. 2 and 5, has a pairof down draft mixture conduits 25, each including an inner venturi tube26 into which discharges a main fuel supply nozzle 27. At the side ofthe carburetor is the fuel supply bowl, generally indicated at 22 inFIG. 3 and 22a in FIG. 5, having parallel partitions or weirs 29,forming a central, constant level chamber 30 and side overflow chambers31. Within chamber 39, is a cylinder 32 for mounting an acceleratingpump and a second cylinder 33 for receiving a suction step-up device.Pivotally mounted in the upper part of the mixture conduit structure, isa butterfly choke valve 3 for which suitable control mechanism (notshown) is provided. A fast idle cam 36 is carried at the end of thechoke shaft 37 for cooperation with an abutment screw 38 on pivotedlever 39 linked to the throttle valve 126 by elements 40 and 41.

At the bottom of constant level chamber 30 are a pair of main meteringorifice elements 42 connected to the main nozzles by cross passages 43.The orifice elements may be controlled by suitably-operated meteringrods or valves. Bowl cover 44 is provided with a vent opening 45, whichmay be connected -to a balance tube opening into the air horn, or to theatmosphere outside the air horn, as desired. An inlet fitting 46 (FIG.5) is mounted in the sidewall of the bowl and is connected by means of atube 18 to main discharge fitting 47 of fuel pump 15. At the bottom ofthe bowl is a second fitting 49 connected by a tube 50 to inlet fitting51 leading to the scavenging portion of the pump, to be describedhereafter. Fitting 49 is connected by a cross passage 52 to ports 53opening into the bottoms of overflow chambers 31. Distinguishingfeatures of the carburetor bowl shown in FIG. 3 will be describedhereafter.

The pump, which is identical in both forms and best shown in FIG. 3,consists of a pair of casing members 56 and 57, having flanges 58 and 59with inclined, abutting faces which clamp the periphery of main pumpingdiaphragm '69. The diaphragm is centrally clamped between washers 61 and6-2, which are shaped at their peripheries to maintain the free flexingportion of the main diaphragm between the washers and casing flanges ina loop or bight 63 extending into the main pumping chamber 64, ascovered in Johnson and White 'Patent No. 2,840,063. An actuating stem 65is centrally secured to the pumping diaphragm and its clamping washersand connected by lever 17 and push rod 16 to the engine cam for causingintermittent motion of the diaphragm in the upward or chargingdirection. The intervening pumping strokes of the diaphragm are producedby expansion of coiled compression spring '66, which bears against theupper surface of diaphragn clamping washer 62. This type of pumpactuating means serves to limit discharge pressure of the pump, whilevarying the discharge volume thereof substantially in inverserelationship to the back pressure in the pump outlet for moderate ratesof diaphragm reciprocation.

Diaphragm clamping flanges 58 and 59 are themselves clamped together andabout the main pumping diaphragm by a sheet metal cup 67 which underliespump body member 56 with intervening gasket 67a and is formed in itsupper portion, as at 68 to embrace and permanently secure together thepump casing flanges and diaphragm. Lower pump body part 56 hastransverse apertures 70 and 71, respectively, receiving outlet checkvalve 72, biased by coil spring 73 seating on a collar 74, and inletcheck valve 75, biased by coil spring 76 seating on a collar 77. Outletcheck 72 cooperates with a seat forming ridge on the periphery of mainpump discharge port 78, while inlet valve 75 cooperates with a similarlyformed seat at the inner extremity of inlet passage 71. Dischargefitting 47 is sealingly secured within an opening in clamping cup 67aligned with discharge passage 70 in the pump body. Inlet fitting 7 9 issimilarly secured within an opening in the clamping cup aligned withinlet passage 71. Fitting 7 9 is connected by tube 13 to the remote fueltank.

Pump body 56 has a generally cylindrical recess 82 at one side which isinwardly concaved at the top, as at 83, to form pulsator chamber 84 ofthe scavenging pump, which is connected by ample passages 85 to mainpumping chamber 64. A scavenger diaphragm 86 traverses pulsator chamber84 and its periphery is clamped against the upper wall of body recess 82by means of a generally cylindrical body sub-member 87 flanged, as as83, for attaching screw 89 which assists clamping cup 67 in maintainingthe assembly. Body sub-member 87 has cross passages 96 and 91,respectively, receiving inlet check valve 92, biased by coil spring 93seated on collar 94, and outlet check valve 95 biased by a coil spring96 seated on a collar member 97. Inlet check valve 92 cooperates with aridged seating annulus formed on inlet passage or port 90, while springseating collar 94 is centrally apertured to connect passage 90 toscavenger pumping chamber 98 beneath scavenger diaphragm 86. 7 Outletcheck valve 95 cooperates with a seating ridge on discharge port 99 alsocommunicating with the scavenger pump chamber. Fitting 51 is sealinglysecured in an opening in clamping cup 67 aligned with inlet passage 95while fitting 100 is similarly secured in an opening in cup 67 alignedwith inlet passage 91. Fitting 51 is connected by tube 50 to overflowdrain fitting 49 at the bottom of the carburetor bowl. Fitting 100 isconnected to previouslymentioned tube 14 which returns the overflow tothe fuel tank,

' In the form of carburetor shown as FIGS. Zand 3, main pump dischargetube 18 is connected to fitting 165 opening into inlet port 196 formedin a boss 197 on the side of carburetor fuel bowl 22. Port 106'communicates through a valve seat restriction. 1%. with a chamber 109 Ibeneath a flexible diaphragm 110 normally biased downwardly by a coiledspring 111 seating againstthe upper wall of a chamber'11-2 in cap 113above the diaphragm. Diaphragm 110 is suitably clamped between boss 1137and cap 113 as -by machine screws in bolting flanges provided on theboss and cap. A pin 114, centrally secured to diaphragm 110, carries avalve 115 at its lower extremity for controlling valve seat restriction108. Chamber 109 communicates with the interior of constant levelchamber portion 34 of the fuel bowl through passages 12%. Tube 23connects a fitting 24 opening into pressure chamber 112 above diaphragm119 with intake manifold 29 (FIG. 1). Valve seat restriction 103 isfluted, as at 193a (FIG. 4), so that When valve 114 is seated, or in itsmost restricting position, the restriction is not fully closed, butmerely reduced to its mniimum effective size. If desired, the samefunction may be accomplished by limiting the upward stroke of diaphragm,as by a suitable stop.

During operation of the engine, main pumping diaphragm 66 will be causedto reciprocate by the alternate, opposing actions of cam-actuated pushrod 16 and coil spring 66. During the upward or charging stroke of thediaphragm, caused by cam action, fuel will be drawn from tank 12 pastinlet check 75 into main pump chamber 64. During the downward ordischarge action of the main diaphragm, caused by expansion of springo,this fuel will be forced out through port 78 past discharge check 72 andthrough supply tube 18, port 106, valve seat restriction 108, chamber109, and passages 12% into constant level fuel chamber 30. This fuelwill be available for supply through metering orifice elements 42,passages 43 and main nozzles 27 to the carburetor, where it is mixedwith air and thence delivered by induction through intake manifold 20 tothe engine firing chambers. When liquid fuel in constant level 30chamber reach the top of bafiies or weirs 29, the fuel overflows intooverflow chambers 31.

Pumping action of main diaphragm 60 also acts, by means of the hydrauliclink formed in passages and pulsator chamber 84 to reciprocatescavenging diaphragm 86. During the upward, charging stroke of maindiaphragm 60, a scavenging diaphragm 86 is also drawn upwardly so as todraw fluid through overflow return tube 59 and past inlet check 92 intoscavenging chamber 98. Upon the downward or discharge stroke of maindiaphragm 60, the scavenging diaphragm is caused to move downwardly soas to force fuel drawn into chamber 98 on the previous stroke outwardlythrough tube 14 for return to the tank. Inlet control valve 115 andvalve seat restriction 108 are designed, when valve 115 is drawn fullyupwardly under maximum intake manifold suction conditions, to providesufficient fuel for idling operation of the engine, together with asurplus which passes through the overflow chambers and return tube 50into the scavenging pump and thence is returned to the tank. Thus aconstant, cooling circulation of liquid fuel is maintained through thepump and carburetor even at periods of lowest engine fuel consumption.

Spring 111 acting on valve diaphragm 118 is calibrated to permitdownward or valve opening movement of the diaphragm as the intakemanifold suction. decreases in correspondence with increasing powerdemands on the engine, as accompanied by increasing opening of thethrottle valve or increasing speed of the engine. When the power demandson the engine are greatest so as to require maximum fuel delivery, valve115'will be in its lowermost or least restricting position to providemaximum effective clearance through valve seat restriction 108 foradequate supply of fuel to the carburetor.

During low speed-low power demand-low fuel demand operation of theengine, when intake manifold suction is greatest, i.e., at lowestpressure, valve 115, being in its most restricted position, will createsufficient back pressure Within main pump chamber 64 to limit thedischarge actionof main diaphragm 64 just suhiciently to produce a fullstroke of scavenger diaphragm S6 and to supply slightly in excess of thefuel consumed by the engine to maintain the liquid fuel circulationreferred to above. On the other hand, when the engine power and fueldemands are increased, as sensed by decreased mani- 5 fold suction(increased pressure) the restriction of valve seat 108 around valve 115will be reduced and the back pressure within main pump chamber 64correspondingly reduced to permit an increased stroke of the main pumpand consequent increased fuel delivery.

Since a portion of the main pump capacity is utilized in actuating thescavenger pump and further, in view of the restriction of the supply tothe carburetor at times of low fuel demand, the efficiency of the mainpump may be increased without unduly increasing the fuel supply to thebowl and upsetting metering. In the usual pump carburetor float bowlinstallation, the float actuated needle valve controlling the constantlever chamber can resist limited pressure in the fuel supply line.Supply pressures above that limit tend to unseat the float valve so asto excessively raise the fuel level and abnormally enrich the fuelmixture delivered by the carburetor or even cause flooding and stalling.This condition is eliminated in the present invention. The increasedefliciency of the main pump permits the better handling of vapors andeasier priming of the pump. Such improved efficiency may be achievedeither by increasing the size or stroke of the diaphragm (displacement),or increasing the effective size of the intake and discharge ports andvalves of the pump. Thus, the main pump can more readily purge itself ofair or vapors.

Another advantage of the present invention lies in its anti-stallaction. In case the engine speed should drop because of insuflicientliquid fuel in bowl 30, inlet control valve 115 will be moved to a lessrestricting position, because of the reduced manifold suction. This inturn tends to reduce the pump back pressure and increase the pump strokeand the rate of fuel delivery to the carburetor bowl to remedy theimpending starving condition.

In the modification in FIG. 5, all parts identical with correspondingparts in FIG. 3 are given like reference numerals. Inlet fuel fitting 46is provided with a valving restriction 116 with which a needle valve 117cooperates. The needle valve, in turn, is urged inwardly or toward itsrestricting position by a camming element 118 which slides through vent45 in bowl cover 44, and at its upper extremity, is pivotally connectedat 119 to an arm 120 rigid on a countershaft 121 rotatably supportedabove the bowl cover. At the end of shaft 121, there is secured an arm122 connected by a link 123 to throttle-operating crank 124, which alsoincludes the element 41 previously mentioned, connected to fast idlelink 40. Crank 124 has an apertured arm 125 for connection by suitablelinkage to the usual throttle pedal in the drivers compartment. Thenormal idling position of throttle disc valve 126 is adjusted by meansof a screw 127 which cooperates with the finger 128 formed on throttlecrank 124.

Inlet control valve 117 and its operating linkage is designed so thatwhen the throttle valve is in its normal idling position, valve 117 willbe pushed inwardly to its maximum restricting position in which,however, restriction 116 is not completely closed. Thus, when the engineis operating under low load, low fuel requirement conditions, asnormally accompanied by a restricting position of the throttle valve,fuel delivery fitting 46 will also be restricted. This results inproduction of a back pressure in the main pumping chamber, as occurs inthe previous form under high manifold suction conditions, so as to limitthe stroke of the main pump to just suflicient length to provideslightly more fuel than is needed to satisfy the engine requirements. Asthe throttle valve opens, camming element 118 is lowered to permitrightward or opening movement of needle valve 117 so as to reduce theefiective restriction at 116, thereby resulting in a longer pumpingstroke and greater pump delivery to satisfy the corresponding greaterengine fuel demand.

In each form, the valve-controlled, carburetor fuel inlet restrictionfunctions as a metering valve which adjusts the pump stroke inaccordance with engine fuel demands. Thus, while a constant circulationof cooling liquid is maintained, pump action is not excessive so thatlong life of the pump is assured. Other means of restricting the fuelinlet, which are sensitive to engine fuel requirements, may be provided,such as a speed responsive device, for instance, of the fly ball orinertia type, or a device responding to generator output voltage. Thedetails of the carburetor and pump construction may he altered invarious ways, and these and other modifications may be made, as willoccur to those skilled in the art. The exclusive use of allmodifications as come within the scope of the appended claims iscontemplated.

I claim:

1. In an internal combustion engine, an induction system with a throttletherein, a fuel bowl with an inlet for connection to a source of fuel,means for maintaining a constant head of fuel in said fuel bowl, a valvepositioned in said inlet and movable from a partially closed position toan open position, a device responsive to pressure conditions in saidinduction system, and an operative connection between said device andsaid valve to shift said valve to said position.

2. The combination described in claim 1 in which said device responds topressure conditions in said conduit posterior to said throttle, saidoperative connection causing restriction of said inlet by said valve asthe induction conduit pressure drops, while reducing restriction of saidinlet as said pressure increases.

3. For use with an internal combustion engine having an intake manifold,a fuel supply system comprising a pump, a carburetor having a constantlevel chamber of the overflow type with an inlet for attachment to asource of fuel, a valve in said inlet having structure for restrictingsaid inlet, a device responsive to suction conditions in said manifold,and an operative connection between said device and said valve forshifting said valve to a restricting position as the manifold suctionincreases and opening said valve as the manifold suction drops.

4. The combination specified in claim 3 in which said pump is of thevariable delivery-uniform pressure type whereby pump action and deliveryof fuel are adjusted in accordance with fuel demands of the engine assensed by said suction responsive device and said inlet valve.

References Cited in the file of this patent UNITED STATES PATENTS1,881,860 Muzzy Oct. 11, 1932 2,254,850 Mallory Sept. 2, 1941 2,409,965Udale Oct. 22, 1946 2,633,342 Baker Mar. 31, 1953 2,846,203 Voss et a1.Aug. 5, 1958 2,905,455 Eberhardt Sept. 22, 1959

